Apparatus for curing a moldable object with carbon dioxide



March 10, 1959 L. R. ZIFFERER APPARATUS FOR A MOLDABLE OBJECT WITHCARBON DIOXIDE FilOd ll) 6, 1957 4 Sheets-Sheet 1 PMJ- Paul A TTORNEYSMarch 10, 1959 L. R. ZIFFERER- 2,876,510 APPARATUS FOR CURING A MOLDABLEOBJECT WITH CARBON DIOXIDE Filed May 6, 1957 4 Sheets-Sheet 2 PM d- PaulA TTORNEYS APPARATUS FOR CURING A MOLDABLE OBJECT WITH CARBON DIOXIDEFiled May 6, 1957 March 10,1959 L. R; ZIFFERER 4 Sheets-Sheet 32,876,510 APPARATUS FOR CURING A MOLDABLE OBJECT WITH CARBON DIOXIDEFiled May 6, 1957 March 10, 1959 R. ZIFFERER 4 Sheets-Sheet 4 Haw.

,1 ENERG/ZED ENEEG/ZED A TTORNEYS APPARATUS FOR CURING A MOLDABLEOBJECT.

This invention relates to an apparatus and method for curing or settinga molded granular object, and particularly relates to the curing of amold, core, ladle lining or the like, used in founding operations andhereinafter referred to collectively as a sand form.

This application is a continuation-in-part of my copending applicationSerial No. 608,096, filed September 5, 1956, now Patent No. 2,824,345,issued Feb. 25, 1958.

In the aforementioned co-pending application I have pointed out that itis important to cure a'sand form, which has been mixed with water glass,by evacuating, forcing carbon dioxide under pressure into the sand form,re-evacuating, and again forcing carbon dioxide under pressure into thesand form. It is an object of this invention to provide an improvedapparatus for carrying into elfect the method of the aforementionedpatent, and it is a further object to provide an improved method whereinthe applicable pressures during the individual stages of treatment ofthe sand mold are controlled within predetermined and critical limits.

Other objects and advantages of this invention, including the simplicityand economy of the same, will further become apparent hereinafter and inthe drawings, whereof: i

Fig. 1 is a side elevation view showing one specific form of apparatushaving features of construction in accordance with this invention, theapparatus being shown in an open position preparatory to placing thesand form into the curing chamber;

Fig. 2 is a view similar to 'Fig. 1, showing the upper portion of theapparatus, and .showing'the apparatus in position for curing the sandform;

Fig. 3 is a sectional view taken as indicated by the lines and arrowsIII-III which appear in Fig. 2;

Fig. 4 is a. sectional view taken as indicated by the lines and arrowsIVIV which appear in Fig. 3;

Fig. 5 is a perspective view, broken away, showing an upper corner ofthe curing chamber which constitutes a portion of the apparatus;

Fig. 6 is a perspective view, broken away, showingthe cage in which thesand forms are placed in accordance with the practice of this invention;

Fig. 7 is a view in elevation showing the interior of the cage, withsand forms occupying a portion of the space therein and with blanksoccupying another portion of said space;

Fig. 8 is a diagram showing the operative connections of the controlelements which operate in accordance with the method of this invention;and

Figs. 9 and 10 are two detailed diagrams showing the raising andlowering of a cover plate in the operation of the apparatus.

Turning now to the particular form of the invention selected forillustration in Figs. l-3 of the drawings, the number It designates achamber having a closed bottom and sides, which is open at the top. Thechamber 10 is supported in a fixed posit-ion on a pair of opposed,upright slide members 11, 11. Also mounted on the slide members 11, 11is a pair of carriage members 12 mounted on slides 13 which areslideable up and down the upright slide members 11. Each of the carriagemembers 12 is secured to the top of a cover plate or lid 14 whichcarries along its lower surface a gasket 15,

which may be a rubber O-ring or the like. The cover plate 14 isreciprocable up and down toward and away from the chamber 10.

Suspended from the cover plate 14 is a cage member 16 having a pair ofsides and a bottom but which is open at the other two sides. The cagemember constitutes a supporting member for one or more sand forms 8which are to be treated in accordance with the process of thisinvention.

The number 20. designates a cylinder which is vertically arrangedalong aline co-extensive with the path of reciprocation of the cage 16 up anddown. The cylinder 20 is stationary, and has a piston member 21 whichhas capacity to reciprocate up and down, conforming with theaforementioned movement of the cover plate 14 and cage member 16.

Means are provided for subjecting the sand mold S alternately to theaction of vacuum and the action of carbon dioxide. It will be observedthat the chamber 10 has a vacuum gauge 19 and a vacuum line 22 leadingto a vacuum pump or accumulator tank, as will further appear. The number23 designates a vacuum valve solenoid which is connected to control thevacuum valve 24. Similarly, the number 25 designates a pipe extending toa source of carbon dioxide, and the carbon dioxide valve 26 iscontrolled by a valve solenoid 27.

Means are provided for regulating the movement of the cage 16 up anddown with respect to the chamber 10. The number 30 designates a two-waybleed valve carried on the upper end of the cylinder 20, which admitsair above the piston, permitting the gradual. descent of the cage 16into the chamber 10. It will be observed that one of the slides 13carries a switch trip 31 which is arranged to contact a microswitch 29when the cover plate 14 is about to contact the upper surface or rim ofthe chamber 10. The microswitch 29 is connected to actuate the cylinder20 in response to the closure of the chamber 10 as heretofore described,thereby applying pressure downwardly upon the cover 14, maintaining thelid '14 tightly secured against the opening of the chamber 10, therebysealing said chamber. Means are also provided for opening the chamberafter the completion of the curing operation, as will be furtherexplained hereinafter.

Referring further to Figs. 1 and 2, the number 32 desi nates a timerwhich is connected to cause the automatic operation of the apparatus.The timer is connected to a solenoid 33 operating a valve 34 causing airto lift the piston 21, and the timer 32 is also connected to a solenoid35 which operates a valve 36 connected to the cylinder 20 to cause saidcylinder to press downwardly on the cover plate 14. The timer 32 is alsoautomatically con nected to actuate other portions of the apparatus, aswill further appear in detail hereinafter.

Means are provided for presenting a clean surface at the upper rim ofthe chamber 10, when the lid or cover plate 14 is descending and theapparatus is being closed. It will be observed that, at the uppercorners of the chamber 10 a plurality of air tubes are provided, suchtubes being actuated through an air line 1. 0 controlled from a valve 41and connected to air nozzles 42. The air nozzles 42, which are moreclearly shown in Fig. 5 of the drawings, are directed along the uppersurfaces of the four side walls of the chamber 10. They serve to blowany sand or other loose material off the upper surface of the rim,thereby permitting the formation of a sound air-tight connection betweenthe cover plate 14 and the close again when the limit of downwardmovement is reached. The rod 44 isspring-urged toward its closedposition, and when the cover plate 14 moves upwardly, the

actuating rod 43 also moves upwardly, permitting the rod 44 to springupward and into its normal closed position.

It is an important and advantageous feature of this invention that thechamber is upright and is closed at the bottom and all sides but open atthe top. Carbondioxide is heavier than the air and the chamber 10accordingly holds over carbon dioxide from one treating cycle to thenext. This results in improved curing and makes possible an equal cureusing a lesser vacuum. Referring to Fig. 6, it will be appreciated thatthe cage member 16 has a multiplicity of perforations 45, which permitthe free flow of the carbon dioxide or any other gas which may bepresent, through the cage member 16 itself. This not only facilitatesthe application of vacuum to the sand form, but has the particularadvantage that when the cage member 16 is moved upwardly at thecompletion of a cycle, the heavier carbon dioxide is not agitated to anyappreciable extent and remains in the chamber 10 for further use.

Fig. 7 shows another factor which results in a considerable saving ofcarbon dioxide. It will be observed that, when only a small percentageof the total volume of the cage 16 is filled with sand forms S, a largepercentage of the remaining volume can be filled with blank cubes 3,such blanks being ordinary blocks made of wood or any other suitablesubstance. The blanks B not only result in the saving of carbon dioxidebut also decrease the cost and time necessary for each vacuum treatment.

Turning now to Fig. 8 of the drawings, the operative connections of thecontrolling elements for the apparatus will be observed in furtherdetail. The number 50 designates a source of carbon dioxide underpressure and the number 51 designates a heat exchanger which is adaptedto heat the carbon dioxide as it passes through the pipe 25. The number52 designates a carbon dioxide pressure control, which is connected foroperation by the timer 32 in a manner further to be describedhereinafter.

The number 53 designates an accumulator tank having appropriate valvefittings, and a vacuum pump 54 is connected into the circuit with theaccumulator tank 53.

In the operation of the apparatus, it is to be assumed that the coverplate 14 is elevated as shown in Fig. 8, and that the air, vacuum andcarbon dioxide valves are closed. The operator places one or more sandforms S into the cage member 16, and closes the main switch to the timer32. The push button 63 on timer 32 is pressed which closes solenoidvalve 34 (see Fig. 9) which normally operates to lift the piston of thecylinder 20. Air then flows in through the bleed 30 on valve 36, throughpipe 55 into the top of cylinder 20 and out through the pipe 56 andbleed 57 on valve 34, permitting the gradual descent by gravity of thecage member 16. Just when the cover plate 14 closes, the switch trip 31contacts the microswitch 29, which, through a cam 60 of the timer .32,energizes the solenoid 35 and opens the valve 36, see also Fig. 10,admitting air under pressure on top of the plstomforcing the cover plate14 downwardly upon the upper rim of the chamber 10. Concurrently, whilethe cover plate 14 is descending, the members 43, 44 coact with oneanother to operate the air nozzles 42 to provide a short burst of air toclean off the upper surfaces of the chamber rim. With the revolution ofthe timer, the cam 61 operates the vacuum control valve 24, evacuatingthe chamber. Due to the action of cam 61, the valve 24 closes after apredetermined time. The cam 62 then opcrates the carbon dioxide controlvalve 26 U? admit cari 4 bon dioxide to the chamber. When the carbondioxide pressure reaches a predeterminedvalue, the pressure control 52is actuated, thereby closing the carbon dioxide control valve, limitingthe-maximum carbon dioxide pressure. After a predetermined time, the cam62 closes the valve 26. The cam 61 then again opens and then closes thevacuum control valve 24. With further revolution of the timer, under theinfluence of cam 62 the carbon dioxide control valve 26 is opened, againadmitting carbon dioxide into the chamber 10, and later closing thevalve 26. At the completion of this series of steps, the timer has shutthe vacuum and carbon dioxide control valves and cam 60 closes the valve36 and push button 63 is released to open valve 34, applying pressureunderneath the piston of cylinder 20, as seen in Fig. 8, lifting thecover plate 14 to facilitate the removal of the finished sand forms S.Such lifting action is gradual, and is controlled by air bleeding outthrough bleed 30 on valve 36. It is an important safety factor that thecage descends by gravity, and without pressure from the cylinder 20.Should the operator inadvertently place his hand between the cover plateand the upper rim of the chamber 10, no harm will be done since theforces acting on his hand are simply due. to weight of the apparatus,without air pressure. Air pressure can be applied only when the lid issubstantially completely closed, at which time it would be impossiblefor an operator to expose himself to danger. The relative values of thepressure and degrees of vacuum in accordance with this invention areimportant and critical. It is important that this apparatus be sogoverned that the chamber is exhausted to a vacuum of about 25 to 29.9inches of mercury, carbon dioxide is then introduced at a pressure ofabout minus 3 to plus 3 pounds per square inch gauge, a vacuum of about25 to 29.9 inches of mercury is again applied, carbon dioxide is againintroduced to a pressure of about minus 3 to plus 3 pounds per squareinch, and the chamber door is opened. It has been found that, when theprocessing steps are practiced in the apparatus as described herein, thecritical limitations just expressed enable an operator to produceexcellent mold curing on sand forms comprising particles of materialwhich are previously mixed with sodium silicate.

. Although very satisfactory operation can be obtained without using theaccumulator tank 53, its use has considerable advantage. When molds arebeing treated which require an exceptionally hard cure, an advantage isgained in employing the terminal vacuum of the pump 54 which is higherthan can be obtained in the chamber by use of the accumulator tank 53.When the pump 54 is used directly, the settings on the automatic timer32 are changed to provide a longer time for the vacuum stages of themachine cycle. When less critical work is being treated, the use of thevacuum accumulator tank 53 greatly shortens the machine cycle time.

Although this invention has been described with particular reference tospecific forms of the apparatus, it will be appreciated that variouschanges may be made in the apparatus and method without departing fromthe scope of this invention. For example, equivalent elements may besubstituted for those specifically shown and described, certain featuresof the invention may be used independently of other features, and partsof the apparatus may be reversed, all within the spirit and scope of theinvention as defined in the appended claims.

Having thus described my invention, I claim:

1. Apparatus for curing a sand form with carbon dioxide comprising asupport, a chamber fixed on said support having closed bottom and sidesbut open at the top, a cover plate carried by said support, actuatingmeans connected to cause relative movement of said chamber and coverplate to open and close said chamber, and a cage depending from saidcover plate and extendable into said chamber below the top thereof, saidcage having a plurality of openings therein, means for evacuating saidchamber, and means for introducing carbon dioxide into said chamber.

2. The apparatus defined in claim 1, wherein said cover plate issupported by a fluid actuated cylinder disposed above said cover plate,and wherein means are provided for inactivating said cylinder causingsaid cover plate to descend by gravity to close said chamber.

3. The apparatus defined in claim 2, wherein an automatic meansresponsive to movement of said cover plate is connected for actuatingsaid cylinder as said cover plate reaches the top of said chamber.

4. The apparatus defined in claim 1, wherein an air jet means is locatedat the upper edge of said chamber, and directed to blast any looseparticles off said edge to provide a tight seal.

5. The apparatus defined in claim 4, wherein an automatic actuatingmeans is connected to actuate said air jet means, said automaticactuating means being located in the path of descent of said coverplate.

6. Apparatus for curing a sand form with carbon dioxide comprising achamber open at the top, a cover plate, actuating means connected tocause relative movement of said chamber and cover plate to open andclose said chamber, and a cage depending from said cover plate andextendable into said chamber below the top thereof, said cage having aplurality of openings therein, means for evacuating said chamber, meansfor introducing carbon dioxide into said chamber, and a plurality ofremovable blocks carried by said cage and occupying surplus space insaid chamber.

7. Apparatus for curing a sand form with carbon dioxide comprising achamber open at the top, a cover plate, actuating means connected tocause relative movement of said chamber and cover plate to open andclose said chamber, and a cage depending from said cover plate andextendable into said chamber below the top thereof, said cage having aplurality of openings therein, means for evacuating said chamber, meansfor introducing carbon dioxide into said chamber, and means connected tocause the automatic actuation of said evacuating means and said carbondioxide introducing means.

8. Apparatus for curing a sand form with carbon dioxide comprisinga,support, a chamber fixed on said support having a closed bottom andsides but open at the top, a cover plate carried by said support, apneumatic cylinder connected to cause movement of said cover plate upand down to open and close said chamher, and a cage depending from saidcover plate and extendable into said chamber below the top thereof, saidcage having a plurality of openings therein, means for evacuating saidchamber, means for introducing carbon dioxide into said chamber,automatic valves and actuators connected to said evacuating means and tosaid carbon dioxide introducing means, and means for actuating saidpressurizing means when the carbon dioxide pressure in the chamberreaches a predetermined value.

References Cited in the file of this patent UNITED STATES PATENTS591,168 Hernzerling Oct. 5, 1897 825,088 Thom July 3, 1906 876,783Dresler Jan. 14, 1908 1,165,306 Allen et al Dec. 21, 1915 1,335,222Davis Mar. 30, 1920 1,421,791 Lemoine July 4, 1922 2,205,650 HagemeyerJune 25, 1940 2,294,530 Wiese Sept. 1, 1942 2,367,648 Nichols Jan. 16,1945 2,463,218 Travis Mar. 1, 1949 2,547,323 Hener Apr. 3, 1951

